params.h (ALLOW_STORE_DATA_RACES): New.

	* params.h (ALLOW_STORE_DATA_RACES): New.
	* params.def (PARAM_ALLOW_STORE_DATA_RACES): New.
	* Makefile.in (expr.o): Depend on PARAMS_H.
	* machmode.h (get_best_mode): Add argument.
	* fold-const.c (optimize_bit_field_compare): Add argument to
	get_best_mode.
	(fold_truthop): Same.
	* ifcvt.c (noce_emit_move_insn): Add argument to store_bit_field.
	* expr.c (emit_group_store): Same.
	(copy_blkmode_from_reg): Same.
	(write_complex_part): Same.
	(optimize_bitfield_assignment_op): Add argument.
	Add argument to get_best_mode.
	(get_bit_range): New.
	(expand_assignment): Calculate maxbits and pass it down
	accordingly.
	(store_field): New argument.
	(expand_expr_real_2): New argument to store_field.
	Include params.h.
	* expr.h (store_bit_field): New argument.
	* stor-layout.c (get_best_mode): Restrict mode expansion by taking
	into account maxbits.
	* calls.c (store_unaligned_arguments_into_pseudos): New argument
	to store_bit_field.
	* expmed.c (store_bit_field_1): New argument.  Use it.
	(store_bit_field): Same.
	(store_fixed_bit_field): Same.
	(store_split_bit_field): Same.
	(extract_bit_field_1): Pass new argument to get_best_mode.
	(extract_bit_field): Same.
	* stmt.c (store_bit_field): Pass new argument to store_bit_field.
	* doc/invoke.texi: Document parameter allow-store-data-races.

From-SVN: r176824

5 files changed, 105 insertions, 0 deletions

diff --git a/gcc/testsuite/c-c++-common/cxxbitfields-2.c b/gcc/testsuite/c-c++-common/cxxbitfields-2.c
new file mode 100644
index 0000000..b98b56d
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cxxbitfields-2.c
@@ -0,0 +1,19 @@
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 --param allow-store-data-races=0" } */
+
+/* Test that we don't store past VAR.K.  */
+
+struct S
+{
+  volatile int i;
+  volatile int j: 32;
+  volatile int k: 15;
+  volatile char c[2];
+} var;
+
+void setit()
+{
+  var.k = 13;
+}
+
+/* { dg-final { scan-assembler-not "movl.*, var" } } */
diff --git a/gcc/testsuite/c-c++-common/cxxbitfields-3.c b/gcc/testsuite/c-c++-common/cxxbitfields-3.c
new file mode 100644
index 0000000..6fc4876
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cxxbitfields-3.c
@@ -0,0 +1,21 @@
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 --param allow-store-data-races=0" } */
+
+/* Make sure we don't narrow down to a QI or HI to store into VAR.J,
+   but instead use an SI.  */
+
+struct S
+{ 
+  volatile int i: 4;
+  volatile int j: 4;
+  volatile int k: 8;
+  volatile int l: 8;
+  volatile int m: 8;
+} var;
+
+void setit()
+{ 
+  var.j = 5;
+}
+
+/* { dg-final { scan-assembler "movl.*, var" } } */
diff --git a/gcc/testsuite/c-c++-common/cxxbitfields-4.c b/gcc/testsuite/c-c++-common/cxxbitfields-4.c
new file mode 100644
index 0000000..a2d55f4
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cxxbitfields-4.c
@@ -0,0 +1,18 @@
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 --param allow-store-data-races=0" } */
+
+struct bits
+{
+  char a;
+  int b:7;
+  int c:9;
+  unsigned char d;
+} x;
+
+/* Store into <c> should not clobber <d>.  */
+void update_c(struct bits *p, int val) 
+{
+    p -> c = val;
+}
+
+/* { dg-final { scan-assembler-not "movl" } } */
diff --git a/gcc/testsuite/c-c++-common/cxxbitfields-5.c b/gcc/testsuite/c-c++-common/cxxbitfields-5.c
new file mode 100644
index 0000000..69e4e10
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cxxbitfields-5.c
@@ -0,0 +1,29 @@
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 --param allow-store-data-races=0" } */
+
+#include <stdlib.h>
+
+struct bits
+{
+  char a;
+  int b:7;
+  int c:9;
+  unsigned char d;
+} x;
+
+struct bits *p;
+
+static void allocit()
+{
+  p = (struct bits *) malloc (sizeof (struct bits));
+}
+
+/* Store into <c> should not clobber <d>.  */
+/* We should not use a 32-bit move to store into p->, but a smaller move.  */
+void foo()
+{
+  allocit();
+  p -> c = 55;
+}
+
+/* { dg-final { scan-assembler-not "movl\t\\(" } } */
diff --git a/gcc/testsuite/c-c++-common/cxxbitfields.c b/gcc/testsuite/c-c++-common/cxxbitfields.c
new file mode 100644
index 0000000..43c840b
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cxxbitfields.c
@@ -0,0 +1,18 @@
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 --param allow-store-data-races=0" } */
+
+/* Test that we don't store past VAR.A.  */
+
+struct S
+{
+  volatile unsigned int a : 4;
+  unsigned char b;
+  unsigned int c : 6;
+} var;
+
+void set_a()
+{
+  var.a = 12;
+}
+
+/* { dg-final { scan-assembler-not "movl.*, var" } } */